JPS62136161A - Network control unit - Google Patents

Abstract

PURPOSE:To prevent malfunctions of an autodialer, by fitting a current detecting device which detects a closed loop current which is made to flow when a public telephone circuit is closed for DC to the connecting line of the public telephone line and a telephone set so that it can be recognized that whether or not the public telephone line is already closed by the telephone set. CONSTITUTION:When a command for auto-dialing is sent to a control unit 12 from a terminal equipment 18, the controller 12 checks the output of a current detecting device 3. When the output of the device 3 is low in level, the control unit 12 discriminates that a telephone set 14 is busy and sends status information 'public telephone line is busy and no dialing is possible' to the terminal equipment 18. When both outputs of the current detecting equipment 3 are high in level, the control unit 12 discriminates that the telephone set 14 is in an on-hook state and checks the output of a call detecting device 19. When a call signal is detected, the control unit 12 sends status information 'an incoming call exists and no dialing is possible' to the terminal equipment 18.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a network control device that is connected in parallel with a telephone connected to a public telephone line, determines whether the telephone is in use, and automatically makes a call. .

2. Description of the Related Art Conventionally, when a network control device branches off a public telephone line and connects it in parallel with a telephone to automatically make a call, there is no way to know whether the public telephone line is already being used by a telephone.

FIG. 2 is a diagram showing an embodiment of a conventional network control device. In FIG. 2, 21 is a network control device, which shares the public telephone line 2 with the telephone 14. 16 is a line closing device, which includes a switching element 16 and a low frequency transformer 1.
It is connected to the terminal device 18 via 7. Reference numeral 19 denotes a call detection device for detecting a 16H2 call signal received from the exchange via the public telephone line 2.

20 is a dialer device for sending a dial signal to the public telephone line 2;

Next, the operation will be explained. When the control device 22 receives an automatic dialing command from the terminal device 18, the call detection device 19
If there is no calling signal, the switching element 16 is closed and a direct current for starting the exchanger is passed through the primary side of the low frequency transformer 17. After about 3 seconds have elapsed, the dialer device 20 is activated to send out a dialing signal and send the status information "dialing completed" to the terminal device 18. When the output of the call detection device 19 is checked, it is determined that the If a signal is detected, it sends status information to the terminal device 18 indicating that a call is incoming and dialing is not possible.

As described above, before dialing, there is no means to check whether the telephone 14 is in use or not, and it is possible that automatic dialing may occur even though the telephone 14 is in use.

Problems to be Solved by the Invention When such a conventional network control device is connected to share the same public telephone line as a telephone, the conventional network control device prevents the telephone from connecting to the public telephone line before making an automatic call. Since it was not possible to confirm whether the telephone was being used, there was a possibility that a call using the telephone would conflict with the dialing operation of the network control device.

Means to Solve the Problem The present invention installs a galvanometer device on the connection line between the public telephone line and the telephone set to detect the closed loop current that flows when the public telephone line is connected in a direct current manner. This allows the phone to recognize whether the connection has already been closed.

Effects of the present invention With the above-described configuration, it is possible to detect whether a public telephone line is closed or not, and to prevent an automatic call from being made when a telephone call is being made.

Example FIG. 1 shows an example of the configuration of a network control device according to the present invention.

1 is a network control device, and 2 is a public telephone line. Reference numeral 3 denotes a galvanometer device, in which a parallel circuit of photocouplers 4 and 5 and light emitting diodes 6 and 7 is inserted in the middle of one signal line of the public telephone line 2 that enters the network control device. 8 and 9
are the transistors of the photocouplers 4 and 6, and when current flows through the public telephone line 2, one of the light emitting diodes 6
Or 7 emits light and the transistor 8 or 9 receives the light.
turns on. When transistor 8 or 9 turns on, resistor 1
Current flows through o or 11. 12 is a control device connected to the collectors of transistors 8 and 9 of photocouplers 4 and 5, which are the outputs of the galvanometer device 3, so that when current flows through the public telephone line 2, the output signal of the galvanometer device 3 is It is possible to detect when the signal becomes low level. 13 is a switch; 14 is a telephone; the public telephone line 2 is connected to the telephone 14 via the switch 13; 16 is a line closing device;
16 is a switching element, and 17 is a low frequency transformer. When the switching element 16 is turned on, a direct current flows through the primary side of the low frequency transformer 17 to start up the exchange at the exchange. 18 is a terminal device, which can be connected to the public telephone line 2 via a low frequency transformer 17 and a switching element 16 in an alternating current manner. Further, the terminal device 18 is connected to the control device 12 and can exchange control information.

Reference numeral 19 denotes a call detection device, which detects a 1 sHz call signal coming from the exchange via the public telephone line 2, and its output is connected to the control device. 2o is a dialer device, which is driven by the control device 12 and sends a dial signal to the public telephone line 2.

Next, the operation will be explained. When the terminal device 18 sends an automatic dialing command to the control device 12, the control device 12
Check the output of the galvanometer device 3. Galvanometer device 3 is telephone 1
The transistor 8 or 9 of the photocoupler 4 or 6 is turned on by the current flowing when the photocoupler 4 is off-hook (or when the line closing device 16 is closing the line). Therefore, when the output of the galvanometer device 3 is at a low level, the control device 12
It is assumed that the telephone set 14 is in use and sends status information to the terminal device 18 stating that ``the public telephone line is currently in use and cannot be dialed.''

When both outputs of the galvanometer device 3 are at a high level, the telephone 14 determines that it is in an on-hook state and checks the output of the call detection device 19. When a calling signal is not detected, the switch 13 is opened, the switching element 16 of the line closing device 16 is closed, and a direct current for starting the exchange is passed to the primary side of the low frequency transformer 170. After 3 seconds have elapsed, the dial signal 20 is driven, a dial signal is output, and the status information "dialing completed" is sent to the terminal device.

If a call signal is detected when the call detection device 1e is checked, it sends status information to the terminal device 18 indicating that "a call is being received and cannot be dialed."

Effects of the Invention As described above, according to the present invention, a collision in which a network control device mistakenly dials automatically during a telephone conversation can be avoided by extremely simple means.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a network control device according to an embodiment of the present invention, and FIG.
The figure is a configuration diagram of a conventional network control device. 1... Network control device, 2... Public telephone line, 3... Galvanometer, 4, 6... Photo coupler, 12... ...control device, 13...
・Switch, 14...Telephone, 1S...
Line closing device, 18...Terminal device, 19...
...Call detection device, 2o...Dial signal.

Claims (1)

[Claims] A galvanometer device that is connected to a public telephone line, a telephone, and a connecting cable and detects the current flowing through the connecting cable; a ring detection device that detects a ringing signal from the public telephone line; a switch to control, a line closing device to close the public telephone line in a direct current manner, a dialer device to send a dial signal to the public telephone line, and a control device for controlling the dialer device, the switch, and the line closing device. a network control device comprising: a control device connected to the output of the galvanometer device and the output of the call detection device; and a terminal device that sends control information to the control device and communicates via the public telephone line; .